Moir superstructures in marginally twisted NbSe2 bilayers

The creation of moir & eacute; superlattices in twisted bilayers of two-dimensional crystals has been utilized to engineer quantum material properties in graphene and transition metal dichalcogenide semiconductors. Here, we examine the structural relaxation and electronic properties in small-angle twisted bilayers of metallic NbSe2. Reconstruction appears to be particularly strong for misalignment angles theta(P )< 2.9(degrees) and theta(AP )< 1.2(degrees) for parallel (P) and antiparallel (AP) orientations of monolayers' unit cells, respectively. Multiscale modeling reveals the formation of domains and domain walls with distinct stacking, for which density functional theory calculations are used to map the shape of the bilayer Fermi surface and the relative phase of the charge density wave (CDW) order in adjacent layers. We find a significant modulation of interlayer coupling across the moir & eacute; superstructure and the existence of preferred interlayer orientations of the CDW phase, necessitating the nucleation of CDW discommensurations at superlattice domain walls.